The foreign institutional investors (FIIs) were net buyers to the tune of Rs 20.41 crore in the futures & option segment on Thursday.According to data released on the NSE website, FIIs were net buyers of index futures to the tune of Rs 367.89 crore, and they bought index options worth Rs 83.74 crore. They were net sellers of stock futures to the tune of Rs 433.83 crore while they bought stock options worth Rs 2.61 crore.As per data available on the Sebi website - FIIs were net buyers of stocks worth Rs 204 crore in the spot market on the Tuesday. Domestic mutual funds (MFs) bought shares worth Rs 142.38 crore on the same day.